My ek dial has 20 main marks. My typical recipe with a behmor brewer:
ek at 7.5, behmor has 1 min bloom, 199f temp
After initial water pulse, remove basket and stir until all grounds are fully wet in slurry. Stir in circular motion again at 2:30 and at 3:30.

When using room temp coffees, my extraction yield for this can easily go above 21%, usually into 23%. When using frozen coffees, I almost never get higher than 20.65%

What gives?

Have you tried adjusting the grind finer for the frozen coffee?

I'd grind a hell of a lot finer and not make any changes to the pre-infusion time, leave it where it is.

The paper published last year found a positive correlation between starting bean temperature and mean particle size. So one would expect higher extraction from colder beans, all else being equal. Maybe it's something else. Or they were wrong.

Are you certain you're doing a fair comparison? Same batch of coffee, some doses direct from the freezer, other doses allowed a couple of hours to warm in a sealed container before grinding?

Maybe since the coffee is cold it's also taking longer to get the temp of the bed up....?

Yeah, that's a possibility. The initial bloom and first infusion would surely be cooler although it's hard to say how much. It would be pretty easy to test: just let the grounds sit for an hour before brewing. It might ruin the coffee though.

jpender wrote:The paper published last year found a positive correlation between starting bean temperature and mean particle size. So one would expect higher extraction from colder beans, all else being equal. Maybe it's something else. Or they were wrong.

Are you certain you're doing a fair comparison? Same batch of coffee, some doses direct from the freezer, other doses allowed a couple of hours to warm in a sealed container before grinding?

I think the point is more "because it's more even you can extract more and still have good tasting results", not "more will be extracted with the same parameters". So maybe grind finer, crank up the temp, or stir more.

Those guys claimed to find two differences with grinding colder beans:

1. Tighter grind distribution
2. Shift toward smaller particles

I was wrong about the mean particle size decreasing. In fact, the mean *increased* for freezer temperature coffee beans versus room temperature. But at the same time, the distribution shifted to smaller particles. That may seem like a contradiction but it's due to the change in shape of the distributions. The result was an increased amount of total surface area in the grinds from freezer beans versus room temperature beans, hence the expectation of faster extraction.

From the paper:

"Grinding colder coffee beans produces a more uniform particle distribution, with a decreased particle size. While the decreased particle size will tend to speed up extraction due to the larger surface area, the increased uniformity should minimise the amount of wasted bean, which is discarded without being extracted to completion."

Of course the obvious answer is to grind finer or increase the water temperature (or stop keeping the coffee in the freezer). But that doesn't really answer the question.

I wonder why nobody else has noticed this? What the OP is doing could be replicated by just about anyone who has a refractometer or equivalent.

I think I'm missing something here, I'd always thought grinding from frozen produced smaller grinds therefore you should grind coarser.

the papers seem to say the same thing.

how come the advice is to grind finer still?